Relays are used in a variety of electrical engineering applications in order to effect switching operations, in particular to drive loads such as motors, lamps, valves etc. conventional relays consist of a magnetic circuit with a magnetic coil (excitation coil) wound onto a core made of magnetically conductive material, with a magnetic yoke, and with an armature held by means of a spring (for example, a metal spring) and a set of contacts with contacts (for example a make contact, a changeover contact and a break contact) and with contact elements The switching characteristics of the relay, i.e. the present switched state (in particular the normal state assumed when there is no excitation and the operate state assumed on reaching the response threshold) is controlled by driving the excitation coil and the effect of this on the set of contacts. Depending on the intensity of the excitation current through the excitation coil, a magnetic field Is produced in the magnetic circuit that causes the contacts in the set of contacts to move as a result of which a specific output signal (an alternating function) is to be generated at the output of the relay (for example to drive the load connected to that output. For example, in the above-mentioned set of contacts that make contact, changeover contact and break contact, the changeover contact is connected to the break contact In the normal state (no current flow in the excitation coil); the changeover contact moves away from the break contact when (excitation) current flows through the excitation coil (this causes a specific force to be applied to the armature) and when a specific intensity of excitation current is reached (at the response threshold of the relay) the changeover contact is drawn onto the make contact.
In order to provide polarity reversal functions, in which the output signal is to exhibit a change in polarity (which is required in many applications, e.g. motor polarity reversal), relay arrangements can be used comprising two interconnected relays with changeover function. To simplify the design of such relay arrangements, components of the magnetic circuit and/or the set of contacts (contacts and/or contact elements) of both relays can be assigned jointly: Usually, a magnetic circuit Is provided comprising two excitation coils that can be driven independently of each other, a common yoke and an unstably mounted armature between the two excitation coils. Furthermore, in the above-mentioned set of contacts, a common break contact can be provided (in addition to the two changeover contacts and the two make contacts). By means of the unstably mounted armature, the contact elements of the set of contacts are operated thus effecting the desired switching behavior at the output of the relay arrangement (output signal polarity change). For example, the make contacts can be "closed" (connected to the changeover contact) by means of two contact springs each connected to a changeover contact. It is advantageous In this relay arrangement with unstably mounted armature that the space requirement, production complexity and therefore the production costs are minimized. It is however disadvantageous that when the unstably mounted armature is in the normal state (i.e., no current flow in the two excitation coils, the armature is pulled away from the two excitation coils by spring force), external acceleration factors cause rattling noises which, in many applications, have a disturbing effect (for example, in the passenger compartment of a motor vehicle: electrically operating window lifters, seat adjusters, sunroof etc.).
The object of the invention is to specify a method that allows the noise emitted by the relay arrangement in the normal state to be reduced in a simple way.